Process for making alkylene carbonates



Patented Oct. 20, 1970 hydrogen bromide, or hydrogen iodide. Preferably, hy-

PROCESS FOR M 1 2 CARBONATES drazlne itself or its hydrochloride is employed.

Albert H. Emmons and Ludo K. Frevel, Midland, Mich., paltlcular advantage of the present improved catalyst assignors to The Dow Chemical Company, Midland, res des 1n the fact that it can be reused for subsequent re- Mich., a corporation of Delaware 5 actions without need for regenerative treatment and with- No Drawing, Fil d F b, 7, 1968, S N 703,535 out substantial loss of efliciency. Normally, the reaction Int. Cl. C07d 13/06 mixture is distilled to separate the alkylene carbonate US. Cl. 260-3402. 4 Claims product, leaving the catalyst as the major component of the distillation residue. This residue can then be recycled directly to the process as the catalyst for a subsequent re- ABSTRACT OF THE DISCLOSURE ti In the reaction of carbon dioxide with an alkylene oxide T alkylene Oxide reactant in the process can be any to make a cyclic carbonate, high conversions and yields are Oxlrahe known to he operhble m the reachoh- The more obtained by using as the reaction catalyst hydrazine or a common compounds of thls class are represented by the hydrazine hydrohalide. The catalyst can be reused in sub- 15 general formula sequent reactions. R

R C\ BACKGROUND OF THE INVENTION This invention concerns the use of a new catalyst where- RILO by improved results are obtainable in the reaction of H carbon dioxide and an alkylene oxide to produce the correh i R, R d R" are h h d ogen, an alkyl radical spondmg cyclic alkylene carbonate The inventwnrarticof 16 carbon atoms, an alkenyl radical of 26 carbon ularly concerns the use of hydrazine or a hydrazme salt atoms, a h l di l, or R and R may be joined to to catalyze the h form a cyclohexane ring and the oxirane compound 1s a The g h f eohdltlons at Whleh Y oxldes and cyclohexene oxide. The formula, therefore, represents 1,2- carbon d1ox1de react to form a cyclic carbonate are well id h as ethylene id propylene oxide, butylene knOWh- Generally, temperatures In the approximate range oxide, octene oxide, butadiene monoxide, styrene oxide,

of ahd shpel'atmospherie P e of about cyclohexene oxide, and methylcyclohexene oxide. 10-300 atmospheres are employed. A reaction temperature of about 160-200 C. and a pressure of 50-150 atmos- EXPERIMENTAL PROCEDURE Pheres are usually Preferred The reactants e used in The reactor was a stainless steel pressure vessel equipped about eqhel1 molar Proportions with the Carbon dioxide with a stirrer, means for measuring the temperature and normally in Slight eXeesS- 4 pressure, and inlets connected to pressurized cylinders of Known catalysts for the reaction include inorganic bases Carbon di id d lk l id Th eactor as such as sodium hydroxide and sodium carbonate and h d ith 5 g, of catalyst (except in Example 2) and Organic nitrogen bases Such as tertiary amines, quaternary some of the desired alkylene carbonate product to act as am bases, and Salts of these nitrogen bases Such a solvent for the catalyst, then it was sealed, pressured to as their carbonates and h e eXamP1e, aliphatic 40 about five atmospheres with carbon dioxide and heated. tertiary amines such as trlmethylamine, aromatic tertlary w h h reactor at about 200 C h reactor was presamines $11011 as Py and quinoline, q e y surized to 300-600 lbs. gauge pressure of carbon dioxide monium hydloXldes h as tetrttethyl p m 3" and alkylene oxide was added intermittently with addition dYOXide, trimethy1 behlyl ammonlhm hydroXlde, dlalkyl of carbon dioxide as required to maintain the original piperidinium hydroxide, and the carbonates, bicarbonates,

pressure. A total of 4 g. moles of alkylene oxide was added and halides of such hydroxides are all known to catalyze and carbon dioxide was added until the reactor pressure the reaction. Catalyst concentrations of 0.1-5 percent based mmained constant f one hour, indicating no further ltg ei of t ll i fie gtev gf t l l g l l r-poSe and reacgonnlfllslight nziolar excgss (at cicarbgn diox(i1de bases BS6 flown ea 3 Y S are e 1 e e on t e a cue oxi e was a sor e an reacte in eac they provide fairly high conversions of the reactants and example y generally good yields of the deslred cyclic carbonates. After cooling and venting theireactor, the crude These Y usually are about 7090 Percent of the action product was analyzed, and in some cases the cycllc theol'etlealcarbonate product was distilled from it. In Example 2 the distillation residue from Example 1 was used to SUMMARY OF THE INVENTION catalyze the reaction. The following experiments were run It has now been found that in the process whereby a at ZOO-210 C. with temperatures sometimes briefly higher cyclic alkylene carbonate is made by reacting an alkylene from the exothermic reaction. Propylene oxide was the oxide with carbon dioxide under superatmospheric presalkylene oxlde reactant In each example.

a Pressure, Time, Conv., Yield, Example No. Catalyst lbs. gauge hrs. percent percent 500 8.5 98.0 99.2 500 6.0 98.0 99.2 Hydrazine dihydrochloride 300-400 1.75 97.0 97.5 Hydrazine dihydrobromide... 300-450 2. O 98. 2 98. 9

sure at a temperature of about l00-250 C. and in the Similarly high conversions and yields of the cyclic carpresence of a catalyst, nearly quantitative conversions of bonate are obtained as shown in the above examples when reactants and yields of carbonate are obtained when the the epoxide reactant is another of the class defined by the catalyst is hydrazine or a hydrogen halide salt thereof. generic formula, for example, ethylene oxide, styrene oxide, octene oxide, cyclohexene oxide, or butadiene mon- DETAILED DESCRIPTION 7 oxide A hydrazine halide catalyst can be the salt of any h Experiments otherwise similar to those shown above drogen halide, i.e., hydrogen fluoride, hydrogen chloride, were performed using pyridine, trimethylamine carbonate,

and tetraethylammonium carbonate as the reaction catalyst. In each case, the conversion of reactants and the yield of cyclic carbonate was each about 90 percent.

We claim:

1. In the process for making an alkylene carbonate which comprises reacting an alkylene oxide with carbon dioxide under superatmospheric pressure at a temperature of about 100-250 C. and in the presence of a catalyst, the improvement wherein said catalyst is hydrazine or the hydrogen halide salt thereof.

2. The process of claim 1 wherein the catalyst is hydrazine.

3. The process of claim 1 wherein the catalyst is hydrazine dihydrochloride.

4. The process of claim 1 wherein the alkylene oxide is propylene oxide.

4 References Cited UNITED STATES PATENTS FOREIGN PATENTS 11/ 1956 Great Britain.

NORMA S. MILESTONE, Primary Examiner 

